
theorem
  for D be non empty set, x1,x2,x3,x4,x5,x6,x7,x8 be Element of D
  holds <* x1,x2,x3,x4 *>^<* x5,x6,x7,x8 *> is Element of (8-tuples_on D)
proof
  let D be non empty set,x1,x2,x3,x4,x5,x6,x7,x8 be Element of D;
  reconsider x1234 = <* x1,x2,x3,x4 *> as Element of 4-tuples_on D
  by LMGSEQ4;
  reconsider x5678 = <* x5,x6,x7,x8 *> as Element of 4-tuples_on D
  by LMGSEQ4;
  D c= D;
  hence thesis by FINSEQ_2:109;
end;
